Apparatus and methods for signal reception based on network load estimations

ABSTRACT

Methods and apparatus for correcting quantization errors in signal reception based on estimated network loading including solutions for preserving cellular network performance in low noise, high interference environments. In one embodiment, a data channel is amplified with respect to other signals based on network load during periods of relatively low network utilization. Dynamic modification of the data channel&#39;s power level is configured to overcome quantization errors, rather than the true noise floor (which is insignificant in low noise environments). Such solutions provide both the fidelity necessary to enable high degrees of unwanted signaling rejection, while still preserving data channel quality.

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BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to the field of wirelesscommunication and data networks. More particularly, in one exemplaryaspect, the present invention is directed to methods and apparatus foradjusting signal reception based on estimations of network load.

2. Description of Related Technology

In telecommunications networks, “orthogonality” refers to systems,processes, signaling, effects, etc. which exhibit desirable exclusionaryproperties. Orthogonal properties are heavily leveraged in multipleaccess communication schemes. Consider an aggregate signal composed ofseveral orthogonal constituent signals. Ideally, a receiver can extracta desired signal from the aggregate signal, and reject the otherorthogonal constituent signals. In this example, each of the orthogonalconstituent signals is removable “interference”.

For example, CDMA (Code Division Multiple Access) based systems utilizea complex series of orthogonal “spreading codes” to distinguish betweeneach data and control channel. A CDMA signal can be separated into itsconstituent channels, ideally without interference between theconstituent channels (i.e., inter-channel interference or ICI).

In contrast to unwanted orthogonal signaling, true noise is“non-orthogonal” and does not exhibit simple exclusionary properties.For example, true noise includes elements such as nearby interferingsystems, thermal noise, transmission effects, etc. Unlike orthogonalsignaling, true noise is largely unpredictable and cannot be removed.Generally, true noise must be corrected using error correctiontechniques, or rendered insignificant to the transmitted signal power.

In typical wireless reception, an RF frontend “conditions” and convertsa received RF waveform to a digital representation for subsequentdemodulation and/or processing. Most designs for RF frontends implementsignal conditioning stages before demodulation and/or processing stages.Also, RF frontends are typically constructed around fixed pointarithmetic for cost and simplicity reasons (i.e., a fixed number ofdigits are used for operations).

Unfortunately, practical design constraints can create artifacts innormal operation. For example, in low noise environments, unwantedorthogonal signals can have much higher transmission power than thedesired signal. These unwanted orthogonal signals will dominate thesignal conditioning operations. As described in greater detailsubsequently herein, such conditions can occur when a mobile device isvery close to a sparsely unoccupied base station (or femtocell). Oncethe unwanted orthogonal signals (such as pilot channels, broadcastchannels, etc.) have been removed, the desired signal is significantlyunder-powered, which can create quantization error effects in fixedpoint circuitry. Quantization errors can lead to much higher bit errorrates (BERs).

Therefore, improved methods and apparatus are needed for handlingscenarios where large differences are observed between knowninterference and desired signals. Such improved methods and apparatusshould ideally facilitate successful decoding of signals, regardless ofthe current cellular conditions. Specifically, new solutions are neededfor preserving cellular network performance, in low-noise,high-interference rejection environments.

Furthermore, it is additionally recognized that correspondingimprovements are needed to existing hardware. Ideally, implementation ofthe aforementioned improved methods and apparatus should not requiresubstantial changes to extant transceiver hardware or software. Thenon-ideal behaviors of hardware-specific implementations should beaccounted for in signal conditioning, demodulation, post-processing,etc.

SUMMARY OF THE INVENTION

The present invention satisfies the foregoing needs by providing, interalia, improved methods and apparatus for adjusting signal receptionbased on one or more estimations of network load.

In a first aspect of the present invention, a method for improvingquantization rejection of at least one signal among a plurality ofsignals and noise is disclosed. In one embodiment, the plurality ofsignals includes at least one other known signal and the methodincludes: transmitting the plurality of signals; receiving informationrelated to an estimated network load based on a measured firstattribute; and adjusting the transmission characteristics of at leastone but not all of the plurality of signals based on the information.

In one variant, the first attribute comprises a ratio of a firstparameter of the network to a second parameter of the network. The firstparameter of the network comprises e.g., a common channel power, and thesecond parameter of the network comprises a total received signal. Thenetwork is compliant with the Universal Mobile Telecommunications System(UMTS) standard(s), and the common channel comprises a common pilotchannel (CPICH).

In another variant, the method includes comparing the receivedinformation to at least one criterion; and based at least in part on theresult of the comparing, selectively performing the transmissioncharacteristics.

In a further variant, the act of adjusting the transmissioncharacteristics includes signal amplification.

In yet another variant, the act of adjusting the transmissioncharacteristics includes lowering the constellation order.

In another variant, the act of adjusting the transmissioncharacteristics includes changing the transmission rate.

In still another variant, the act of adjusting the transmissioncharacteristics includes changing one or more feedback parameters.

In a second aspect of the present invention, a method for enhancing thequantization performance of at least one radio signal among a pluralityof radio signals is disclosed. In one embodiment, the method includes:transmitting the plurality of radio signals, the transmission having afirst radio attribute; receiving information related to a network loadbased on the first attribute; and adjusting the transmissioncharacteristics of at least one of the plurality of signals based on theinformation.

In one variant, the network is compliant with the Universal MobileTelecommunications System (UMTS) standard(s), and the first radioattribute comprises a ratio of a common channel power to a totalreceived signal.

In another variant, the act of generating comprises: comparing the ratioto at least one threshold criterion; and based at least in part on theresult of the comparing, selectively performing the adjusting of thetransmission characteristics.

In still another variant, the at least one radio signal is a dedicatedchannel.

In a further variant, the plurality of radio signals includes at leastone common signal, at least one unwanted signal, and at least one wantedsignal. In one variant, the act of adjusting the transmissioncharacteristics includes signal amplification of the at least one wantedsignal. In another variant, the act of adjusting the transmissioncharacteristics includes lowering the constellation order of the atleast one wanted signal. In yet another variant, the act of adjustingthe transmission characteristics includes changing the transmission rateof the at least one wanted signal. In yet another variant, act ofadjusting the transmission characteristics includes changing one or morefeedback parameters of the at least one wanted signal.

In a third aspect of the invention, a wireless apparatus is disclosed.In one embodiment, the wireless apparatus includes: a wirelessinterface, the wireless interface adapted to receive a plurality ofsignals; logic adapted to determine a network load; a processing devicecoupled to a memory; and a computer program comprising a plurality ofexecutable instructions resident within the memory. When executed by theprocessing device, the program: receives a first signaling channel viathe wireless interface; requests a second signaling channel; estimatesthe network load; and transmits information relating to the estimatednetwork load. One or more reception characteristics of the secondsignaling channel are determined by the information.

In one variant, the wireless interface has multiple fixed pointcapabilities, and the fixed point capability is a receptioncharacteristic determined by the information.

In another variant, the reception characteristic is a target signal tointerference (SIR) level.

In yet another variant, the reception characteristic is negotiated witha serving device.

In still another variant, the information relating to the estimatednetwork load comprises an indication of the first signal channelstrength, relative to the plurality of signals strength.

In a fourth aspect of the present invention, a serving apparatus isdisclosed. In one embodiment, the apparatus comprises: a wirelessinterface, the wireless interface adapted to transmit and receive aplurality of signals; a processing device coupled to a memory; and acomputer program plurality of executable instructions resident withinthe memory. When executed by the processing device, the program:receives a network load estimation via the wireless interface; andresponsively adjusts one or more transmission characteristics of atleast one, but not all, of the plurality of signals.

In a fifth aspect of the invention, a method for compensating for one ormore orthogonal signals having much higher transmission power than auser signal is disclosed. In one embodiment, the orthogonal signalsresult in quantization error in the user signal, and the methodcomprising: obtaining a network load estimation; and responsivelyadjusting one or more transmission characteristics of the user signalbased at least in part on the network load, the adjusting mitigating thequantization error.

In one variant one or more orthogonal signals comprises a pilot channel,and the adjusting the one or more transmission characteristics of theuser signal comprises increasing the transmission power of the usersignal.

In a sixth aspect of the invention, a wireless system is disclosed. Inone embodiment, the system includes a base station and at least one userdevice (e.g., mobile device or UE), and the system is adapted todynamically adjust for quantization errors induced by the noiseenvironment and system parameters by adjusting one or more channelcharacteristics.

Other features and advantages of the present invention will immediatelybe recognized by persons of ordinary skill in the art with reference tothe attached drawings and detailed description of exemplary embodimentsas given below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical illustration of one embodiment of a prior artUniversal Mobile Telecommunications System (UMTS) network comprising aCore Network, a plurality of Base Stations, and a plurality of UserEquipment.

FIG. 2 is a prior art graphical illustration of Automatic Gain Control(AGC) and Analog-to-Digital Conversion (A/D) methods emphasizing theeffects of proper and improper AGC and A/D operation.

FIG. 3 is a graphical representation of one approach for Received SignalStrength (RSS) calculation useful in conjunction with the AGCcalculation of various embodiments of the invention.

FIG. 4 is a logical representation of one exemplary Automatic GainControl (AGC) feedback loop useful in conjunction with the presentinvention.

FIG. 5 is a graphical representation of a signal composition adapted toimprove quantization noise in accordance with one exemplary embodimentof the present invention.

FIG. 6 is a logical flow diagram of an exemplary embodiment of thegeneralized process for improving signal reception based on one or moreestimations of network load, in accordance with the present invention.

FIG. 7 is a logical flow diagram illustrating one exemplaryimplementation of the method of FIG. 6.

FIG. 8 is a block diagram of one embodiment of a generalized servingapparatus configured in accordance with the present invention.

FIG. 9 is a block diagram of one embodiment of a generalized receivingapparatus configured in accordance with the present invention.

FIG. 10 is time and frequency representation of an Orthogonal FrequencyDivision Multiple Access (OFDMA) implementation useful in conjunctionwith various embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to the drawings, wherein like numerals refer tolike parts throughout.

Overview

The present invention provides, inter alia, methods and apparatus foradjusting signal reception based on one or more estimations of networkload. As described in greater detail hereinafter, one exemplaryUMTS-specific implementation obviates the effects of quantization errorsattributed to low noise, high interference environments. Specifically,in low noise environments, the UMTS Common Pilot Channel (CPICH) becomesthe predominant factor in Automatic Gain Control (AGC) calculations,thus when the CPICH is removed, the remaining Dedicated Physical Channel(DPCH) experiences severe (deleterious) quantization effects.

Thus, in one aspect of the present invention, the receiver monitors theload of the network, and requests “enhanced” operation during periods oflow network load. In one embodiment, during such periods of low networkload, the receiver requests increased power levels for its datachannels. For instance, in one UMTS-specific implementation, the UErequests increased levels of DPCH power, when the monitored ratio ofCPICH to the total power spectral density (CPICH/N₀) exceeds a specifiedthreshold. Large values of the foregoing ratio are reasonably correlatedwith periods of low network usage; the total power spectral densityincludes the power allocated to other users.

More generally, various aspects of the present invention encompass awide range of solutions for both monitoring network load, and adjustingsignal reception. For example, one exemplary embodiment describes a UMTSUE (e.g., mobile device) measuring the CPICH/N₀. Other alternativemeasurements include detection of other resources, other transmitters,other receivers, etc. Yet other embodiments are described suitable forother networking technologies, and topologies. Similarly, a UMTS BSadjusting the DPCH power level with respect to the CPICH is alsodescribed. Additional variations and alternate embodiments areconfigured for different coding schemes, transmission rates, hardwareoperation, etc.

Serving apparatus and wireless device apparatus suitable for embodyingvarious other aspects of the present invention are also described. Forexample, in one embodiment, a serving UMTS NodeB can dynamically adjustits DPCH and CPICH power levels to counter expected quantization erroreffects. In yet other examples, the serving UMTS NodeB can dynamicallyadjust constellation order, transmission rate, etc.

Exemplary receiver apparatus are also disclosed. For instance, oneembodiment of a UMTS UE monitors and notifies the UMTS NodeB of networkloading conditions.

Business methods and modes of network optimization are also describedherein.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention are now described indetail. While these embodiments are primarily discussed in the contextof a wireless network having a CDMA air interface, and more specificallyto a UMTS-specific implementation thereof, it will be recognized bythose of ordinary skill that the present invention is not in any waylimited to such CDMA networks or to any particular context (such as theaforementioned UMTS specific implementations). In fact, the principlesof the present invention may be readily adapted to any wireless network,even non-cellular networks, in which the network load is related tounwanted interference levels, thereby affecting the processing of thedesired signal.

For example, it is appreciated that OFDMA (Orthogonal Frequency DomainMultiple Access) based systems must decode the entire radio resourceband (including unwanted time-frequency resources), to successfullyextract the desired time-frequency resources. Common implementations ofan OFDMA front end utilize a large Fast Fourier Transform (FFT)/InverseFast Fourier Transform (IFFT) component to extract channels of interest.Since all time-frequency resources are transformed simultaneously,signal conditioning is performed in aggregate for both desired andundesired time-frequency resources.

Exemplary UMTS Network Architecture—

In the following discussion, a cellular radio system is described thatincludes a network of radio cells each served by a transmitting station,known as a cell site or base station (BS). The radio network provideswireless communications service for a plurality of user equipment (UE)transceivers. The network of BSs working in collaboration allows forwireless service which is greater than the radio coverage provided by asingle serving BS. The individual BSs are connected by another network(in many cases a wired network), which includes additional controllersfor resource management and in some cases access to other networksystems (such as the Internet or MANs).

In a UMTS system, a base station is commonly referred to as a “NodeB”.The UMTS Terrestrial Radio Access Network (UTRAN) is the collective bodyof NodeBs along with the UMTS Radio Network Controllers (RNC). The userinterfaces to the UTRAN via a UE, which in many typical usage cases is acellular phone or smartphone. However, as used herein, the terms “UE”,“client device”, and “end user device” may include, but are not limitedto, cellular telephones, smartphones (such as for example an iPhone™),wireless-enabled personal computers (PCs), such as for example an iMac™,Mac Pro™, Mac Mini™ or MacBook™, and minicomputers, whether desktop,laptop, or otherwise, as well as mobile devices such as handheldcomputers, PDAs, wireless personal media devices (PMDs), such as forexample an iPod™, or any combinations of the foregoing.

FIG. 1 illustrates an exemplary UMTS cellular system 100, with a focuson the radio access network (RAN).

The system 100 includes one or more base station towers 102 (also knownas NodeBs (NBs)), that are set at various fixed geographic locations.Such NodeBs may also be generally referred to as a “macrocell”. EachNodeB provides an area of service coverage 104. The network operatormanages radio access network operation via a Core Network 106. Theunified Core Network provides authentication, accounting, andauthorization (AAA) services, and in some cases, access to externalnetworks (e.g. such as IP Multimedia Subsystems (IMS) services asspecified by the 3GPP). A first UE 108 is shown, operating within thecoverage of the RAN 100.

Furthermore, incipient wireless standards support new network entitiescommonly referred to as “femtocells”; a femtocell provides similarfunctionality to a macrocell, but at a reduced capability and cost, andmay be portable versus fixed. Femtocells may be purchased by a customerfor personal use. The combination of macrocells and femtocells providesa seamless cohesive service from a network operator. Within the UMTSnetwork, femtocells are generally referred to as Home NodeBs (HNBs) 112and have corresponding coverage areas 114.

Each of the cells (macrocells and femtocells where present) are directlycoupled to the Core Network 106 e.g., via broadband access.Additionally, in some networks, the cells may coordinate with oneanother, via secondary access. In the illustrated RAN 100 of FIG. 1, thefemtocells are connected to the Core Network, but are not linked to theother cells of the network. Unlike the broader coverage of themacrocells, a femtocell is generally focused on improving service to afew subscribers. Accordingly, femtocells may have settings andlimitations which are not applicable for the general population. Suchnon-standard settings are generally disclosed, at least in part, withinthe pilot channel public broadcasts. Consequently, the macrocells andthe femtocells may have different pilot channel powers, payloads, andoperation.

While the following discussions are presented in terms of the downlinkpath from the NodeB 102 to the UE 108, it is appreciated that analogousprocesses and structures can be readily implemented within the uplinkpath (from the UE to the NodeB) by one of ordinary skill in the art,given the contents of the present disclosure.

Common Pilot Channel (CPICH) and Dedicated Physical Channel (DPCH)—

The UMTS network utilizes a Common Pilot Channel (CPICH) to provide alluser equipment (UE) with a common synchronization signal. Generally,pilot channels are used for, inter alia, initial “wake-up” and search,estimating potential base station (BS) service reception for handover(i.e. hand-off), etc. Various approaches to pilot channel operation areevidenced throughout the prior art. For example, in Interim Standard 95(IS-95, CDMA), pilot channel measurements are used by mobile devices toinitially determine the existence of base stations, and/or supportmultipath compensation.

The importance of the CPICH to network management and network discoverywarrants a disproportionate share of NodeB 102 transmit resources. Inextreme cases, the UMTS CPICH transmit power can exceed one-fifth (20%)of the total NodeB transmit power. The high power of the CPICH ensuresthat terminal equipment 108 within the coverage area (even at the veryedges) 104 can receive synchronization information. More generally,common “control” channels are the most robust and simplest codedchannels of the network.

The UMTS network also provides Dedicated Physical Channels (DPCH) toprovide channels for control (Dedicated Physical Control Channel(DPCCH)), and data (Dedicated Physical Data Channel (DPDCH)) messagingdevoted to single UEs 108. In contrast to the CPICH, the DPCH is onlyreceived by one recipient UE. Non-recipient UEs cannot decode otherDPCHs. However, the exclusivity of DPCHs still affects overall networkefficiency. Each additional DPCH increases the interference experiencedby all non-recipients. Therefore, network operators generally maximizesystem operation by limiting DPCHs to the minimum power necessary forcommunicating with the intended UE.

UMTS Power Control—

UEs 108 and NodeBs 102 collaborate to control DPCH power using both openand closed loop power control. DPCH target signal quality levels are setand dynamically managed according to existing radio conditions. Forexample, in noisy radio environments, a NodeB boosts DPCH transmit powerto improve UE reception. In lower noise environments, the DPCH transmitpower is lowered. Power control for Dedicated Physical Channels (DPCH)is separated into two (2) loops: (i) outer loop power control, and (ii)inner loop power control.

Outer loop power control manages power control for long term variationsin the radio environment. The UE 108 and the NodeB 102 negotiate andmanage a target SIR (Signal to Interference Ratio) within a RadioResource Connection (RRC) management protocol. The SIR is a predictor ofblock error ratio (BLER) performance; for example, if the received SIRis less than the SIR target, then the BLER is generally poor. The UE andNodeB agree on a SIR target based on the BLER of a reference physicalchannel (DPCH). Within the reference physical channel, there can be oneor more transport channels. The transport channel requiring the smallestblock error rate for acceptable quality is the reference for the SIRtarget. The BLER of the transport channel is the number of bit errorswithin a block or frame after channel decoding and error correction.

Inner loop power control (also known as fast closed-loop power control)is adapted to protect against fast fading. Inner loop power control usesthe same targets set by outer loop control (i.e., derived frompost-processing analysis); however, control is based on the physicalradio connection (PHY layer), and can cycle much faster so as tocompensate for fast fades and the like.

In prior art UMTS operation, the target SIR is determined afterpost-processing gains (removing orthogonal interference components, andapplying spreading gain, etc.); the target SIR is based only on thepower of the received DPCH signal relative to true noise. For example,in one embodiment, DPCH SIR is measured based on a pilot fieldtransmitted within the DPCH. This pilot has a known pattern. The UE canestimate the signal strength of the DPCH by performing an average of thesignal power in the pilot field according to Equation (1) below:S=I ² +Q ²  (Eqn. 1)Where:

S=Signal Strength

I=Magnitude of In-phase Components; and

Q=Magnitude of Quadrature Components.

Additionally, the CPICH noise can be estimated from a variance of thesepilot fields or measured from the CPICH according to Equation (2) below:N _(CPICH)=var(CPICH power)  (Eqn. 2)The noise affecting the CPICH is common to all orthogonal channels.Accordingly, once the noise is measured from the CPICH, the processednoise seen by the DPCH can be derived from N_(CPICH), based on thedifference in Spreading Factors (SF) (or processing gain). For example,N_(DPCH) could be calculated per Equation (3) below:N _(DPCH)=(SF _(DPCH) /SF _(CPICH))*N _(CPICH)  (Eqn. 3)Where:

N_(DPCH)=Noise of DPCH;

SF_(DPCH)=Spreading Factor of DPCH;

SF_(CPICH)=Spreading Factor of CPICH; and

N_(CPICH)=Noise of CPICH

Accordingly, the DPCH SIR is then expressed according to Equation (4)below:SIR _(DPCH) =S/N _(DPCH)  (Eqn. 4)Automatic Gain Control (AGC)—

In addition to power control, typical UMTS receivers 108 also implementvarious forms of signal conditioning, including Automatic Gain Control(AGC). In typical transceiver designs, an Automatic Gain Control (AGC)module amplifies or attenuates the total received signal to maintain arelatively constant signal for receiver digital baseband processing.Unlike power control, AGC operation is performed without any knowledgeof signal quality; in fact, AGC occurs in lockstep with Analog toDigital (A/D) conversion.

Referring now to FIG. 2, various stages 200 of signal conditioning arepresented to emphasize the effects of proper and improper AGC and A/Doperation. Consider the received analog waveform 202. The waveform hasseveral components: (i) a DC offset 204, (ii) high and low frequencynoise 206, and in-band components 208. The RF frontend can remove boththe DC offset and unwanted frequency components in initial filterstage(s). The in-band frequency components 208 are brought to basebande.g., by mixing and filtering out the carrier frequency.

Once the desired frequency components 208 are brought to baseband, theRF frontend must amplify or attenuate the signal for conversion to thedigital representation, such that meaningful digital processes can beperformed. RF frontends are generally implemented within fixed pointarithmetic. In contrast, floating point arithmetic represents numberswith a mantissa and exponent. Fixed point arithmetic can be signed,unsigned, complement, etc. Ideally, the entire dynamic range of theconditioned analog waveform can be fully represented within a fixedpoint A/D conversion. Fixed point operations have a set range, forexample a fixed point eight (8) bit word can only represent 256 numbers(i.e., 2⁸=256). Consequently, the quanta or minimum unit must becarefully chosen to minimize the effects of quantization error.

The first and second digital representations (210, 212 on FIG. 2) of theanalog waveform illustrate the effects of over-amplification, and/or toosmall of quanta, in different implementations. The first fixed pointrepresentation 210 has difficulty representing peaks and troughs of thewaveform; these artifacts saturate the fixed point A/D components,causing distortions or “clipping” effects.

The second fixed point representation 212 illustrates a differentphenomenon which may also be common among alternate receiverimplementations. Instead of “clipping” the over-amplified signal, thesecond fixed point representation “rolls over” creating false artifactsin signal representation. Roll over or wrapping is caused by improperoverflow operation; for example, consider unsigned fixed pointarithmetic having four (4) bits. The maximum value of #1111b (31) cannothandle #10000b (32); thus, the value is truncated to #0000b (0).

Clearly, both the first and second representations 210, 212 areundesirable. In contrast to the first and second representations, thethird fixed point representation 214 of the analog waveform illustratesthe effects of under-amplification, or too large of a quanta. While thethird representation does not generate any “artifacts”, the waveform isnot fully represented. Consequently, quantization error (i.e., thedifference between the actual analog value and quantized digital value)directly causes symbol misinterpretation, and lower effective bit rates(i.e., due to higher BER).

Lastly, the fourth fixed point representation 216 of the analog waveformof FIG. 2 illustrates a properly amplified waveform. The fourthrepresentation can capture the full dynamic range of the analogwaveform, while still providing sufficient clarity to prevent bit errorsin demodulation and processing operations. In some implementations, asmall degree of either clipping or margin may be tolerated or evenpreferable (e.g., to capture more signal fidelity, compensate forfading, bursty transmissions, etc.).

Within the foregoing discussion, it is readily appreciated that therelative complexity and sensitivity of the radio significantly impactthe requirements for fixed point A/D component selection. Simple radiowaveforms in low-noise operating environments, etc. can support fixedpoint components with less resolution. Similarly, complex waveforms,and/or noisy operating environments, require greater bit resolution. Forexample, it is not uncommon for CDMA type receivers to have A/Dcomponents supporting eight (8) or even ten (10) bit resolution. Eight(8) bits of resolution can represent up to 256 (i.e., 2⁸) distinctgradation levels. Ten (10) bits of resolution can represent up to 1024(i.e., 2¹⁰) distinct gradation levels.

Common implementations of AGC use the Received Signal StrengthIndication (RSSI) in a simple feedback loop to adjust for changes in theradio environment. FIG. 3 graphically illustrates one exemplary RSSImeasurement 300. RSSI is calculated as the magnitude (or some derivativethereof) of the In-phase and Quadrature Components of the receivedsignal. FIG. 4 illustrates one exemplary simple feedback loop 400implementing AGC, based on RSSI (such as that obtained using theapproach of FIG. 3). As shown, the RSSI is calculated 402, multiplied bya constant 404, and used as feedback to amplify 406 the incoming signal.Other embodiments may use comparisons between running energy estimationaccumulators, etc.

The AGC constant is dynamically adjusted to correctly capture the entirerange of the signal. For example, if the RSSI increases, theamplification is lowered. If the RSSI decreases, amplification isincreased.

Example Operating Scenario—

Referring now to one exemplary scenario (illustrated in FIG. 5), asingle UE is operating close to a relatively unoccupied NodeB. Recallthat the received waveform comprises at least: the desired or “useful”channel (DPCH) 502, orthogonal or “ignored” channels (e.g., CPICH,signals for other users of the same cell site, etc.) 504, and noise(e.g., thermal noise, interfering cells, etc.) 506.

In the exemplary scenario of FIG. 5, the CPICH 502A dominates over theother elements (e.g., the DPCH 506A, noise 504A, etc.). Unfortunately,once the CPICH channel has been removed, the comparatively under-poweredDPCH is subject to large quantization errors. Thus, as previouslydiscussed, fixed point hardware used in typical wireless devices cannotrepresent the full signal fidelity necessary to separate between usefuland ignored portions of the received signal, including in theaforementioned scenario.

To this end, one aspect of the present invention causes the wirelessdevice and/or base station to adjust target resources based onestimations of network loading. In one exemplary embodiment, a ratio ofthe CPICH to the total received signals is used as an estimate ofnetwork load, although it will be appreciated that other metrics ofnetwork load can readily be used in place of (or in conjunction with)the foregoing ratio approach.

Specifically, in the exemplary embodiment, the CPICH E_(c)/N₀ (alsocommonly referred to as CPICH/N₀) measures the power allocated to theCPICH (E_(c)) relative to the total received power spectral density (N₀;interchangeably designated I₀). Total received power spectral densityincludes both desired signals and unwanted signal interference, asmeasured at the mobile station antenna connector. For example, a highCPICH/N₀ ratio indicates that the NodeB has clear transmission of theCPICH in a relatively noiseless environment; thus, the cell is(ostensibly) not supporting many other DPCHs.

The foregoing network load estimation is used in one implementation fordynamically adjusting a “safety margin”, wherein the adjustment processis adapted to reduce quantization errors. Specifically, a larger safetymargin is used when the CPICH/N₀ power ratio is large (e.g., above −7dB); a smaller safety margin is used when the CPICH/N₀ power ratio islow (e.g., below −7 dB). It is appreciated that while a two-tier model(i.e., above or below −7 dB) is described, any number of different tiersand/or logical hierarchies can be employed if desired, consistent withthe present invention. For instance, a three-tier model having twodifferent safety margins and two thresholds might be used. Upon reachingthe first threshold, the first safety margin is implemented, and if thesecond threshold is reached, the second margin implemented.

When the exemplary receiver notifies the NodeB that a high CPICH/N₀ isdetected, the NodeB responsively boosts the transmit power of thecorresponding DPCH using the safety margin. For example, increasing theDPCH transmit power by 25% is sufficient to remove quantization error inUMTS networks with little to no noise.

The “boost” in transmit power leverages the existing inner loop powercontrol. Specifically, in this example, the NodeB increments its SIRtarget value. Since the NodeB must match a higher level of SIR for theUE, the power for the DPCH allocated to the UE is increased. In thisexemplary case, normal operation of inner loop power control aims to hita target SIR of 0 dB. During corrective operation, the inner loop powercontrol aims to hit a target SIR of 1 dB (approximately 25% moretransmit power, based on a doubling of power for every 3 dB increase).Inner loop power control can change as quickly as once every 0.66 ms inthe illustrated implementation; thus, a certain amount of hysteresis isalso included to prevent excessive “chum” or hunting in target SIR(i.e., once the CPICH/N₀ drops below −7 dB, the enhanced target SIR isstill in effect for a short transitory hysteresis period). As shown, theCPICH 552 still dominates over the other elements; however, the DPCHpower 556 is increased over the noise 554.

Lightly loaded cells will not be affected by the boosted DPCH transmitpower 506B. When other equipment is not present within the cell, theNodeB can focus on increasing the DPCH power to reduce quantizationerror, thereby improving the receiver's call quality. When additionaluser equipment enters the cell, the effects of quantization error arereduced (as noise is increased), thus the NodeB can reduce the safetymargin, or in some cases, revert to normal operation (i.e., noquantization adjustment).

The preceding example is purely illustrative, and other embodiments andvariations are discussed in greater detail hereinafter. For example,alternative systems may measure/receive other indicia, utilize morecomplex adjustment margins or implementation criteria, monitor otherconditional events, etc.

Additionally, while the foregoing examples are framed within a CDMA(Code Division Multiple Access) based UMTS cellular network, it isappreciated that the invention may be widely applied to other systems byartisans having ordinary skill in the relevant arts, given the contentsof the present disclosure. For example, other multiple access schemessuch as OFDMA (Orthogonal Frequency Division Multiple Access), TDMA(Time Division Multiple Access), FDMA (Frequency Division MultipleAccess), and other CDMA based systems, each have analogous elements.

Similarly, other CDMA based schemes (e.g., IS-95, CDMA-2000, etc.) mayutilize other indicia (e.g., pilot channels, synchronization channels,etc.) to estimate network loading, and adjust for quantization error.

Methods—

Referring now to FIG. 6, one embodiment of the generalized intelligentquantization margin procedure for adjusting signal reception based onone or more estimations of network load is described. The operativeelements as described with respect to the methodology 600 of FIG. 6 area client device (e.g., a mobile device, UE, or other user apparatus) anda serving device. Furthermore, the communication link includes at least:(i) one or more desired or “useful” signals, (ii) one or more undesiredor “ignored” interfering signals, and (iii) noise.

At step 602, one or more indicia of related to network load aremeasured. In one embodiment, the indicia are measured at the clientdevice. For example, in the previously described exemplary operation(see “Example Operating Scenario” discussion), the client devicemeasured a ratio of Common Pilot Channel (CPICH) power to the totalreceived signal (N₀) power. It is appreciated that such quantities aresystem dependent; other quantities may be readily substituted. Also, itshould be noted that naming conventions can differ across technologies(e.g., N₀ may be equivalent to RSS (Received Signal Strength), I₀,etc.). In alternative embodiments, the indicia are measured at theserving device.

In one implementation of the invention, the aforementioned indiciainclude power measurements of one or more undesired signals. Forexample, the undesired signals may include at least one beacon signal.In one such variant, a pilot channel power is measured. As previouslynoted, the CPICH channel is typically removed during signal processing.Similar “undesired” signals may include other pilot channels,synchronization channels, common channels, control channels, dedicatedchannels for other users, etc.

At step 604 of the method 600 of FIG. 6, a network load is inferred orestimated, based on the one or more indicia of step 602 (or acombination thereof). In one embodiment, the one or more indicia (or acombination thereof) is/are compared to one or more acceptance or actioncriteria (e.g., threshold levels). One exemplary implementation of theutilizes a single threshold value as previously discussed; above thethreshold, the network is presumed to be lightly loaded, whereas belowthe threshold, the network is presumed to be normally or heavily loaded.In the previously described exemplary operation (see “Example OperatingScenario” discussion above), the client device compared CPICH/N₀ to aset threshold (−7 dB). However, as previously noted, further gradatedscales may be implemented; for example, multiple other thresholds may beestablished throughout the entire range of operation. Empiricallymeasured ratios for CPICH/N₀ can span from −2.5 dB to −24 dB. Forexample, thresholds set at 3 dB increments (e.g., −5 dB, −8 dB, −11 dB,−14 dB, −17 dB, and −20 dB) could be easily implemented within fixedpoint designs.

In alternate embodiments, an estimated network load is deterministicallycalculated based on the one or more indicia (in contrast to comparisonto a simple “yes/no” threshold). For example, the presumed network loadmay vary linearly, exponentially, logarithmically, etc., and thisfunctional relationship can be used to calculate an actual load value inconjunction with the indicia (e.g., CPICH/N₀).

In some embodiments, the estimated network load (or the indicia usefulfor calculating it) is communicated to the serving device, thetransmitting device (e.g., UE) performing the actual determination.Alternately, the estimated network load (or constituent componentsnecessary to perform the calculation) may be calculated at the receiving(e.g., serving) device. In yet other embodiments, the network load maybe estimated by a third party (e.g., a relay device, a master basestation, network-connected third party entity or server, etc.). Forexample, certain technologies utilize other base stations to moderateand manage network operation. One such UMTS specific example includesthe relationship between serving or master base stations, andnon-serving base stations. Future cellular networks (e.g., Long TermEvolution (LTE)) may employ various forms of base stations includingsubstantially limited base stations (e.g., microcells, femtocells,picocells, etc.). Such limited operation base stations may receive someinformation useful for determining network load (e.g., some indicationof the radio resources available for usage, etc.).

As yet another implementation, two or more devices or entities maycooperate in a “distributed” fashion, such as where the UE performs someof the calculation or pre-processing of data, and then sends thepre-processed data to the server (or other entity) to completeprocessing. This approach can ostensibly save on upstream communicationbandwidth, yet at the expense of increased processing overhead (andpower consumption) at the client.

At step 606, the serving device adjusts signal transmission based on theinferred or estimated network load. In one exemplary embodiment, thepower level of the one or more desired or “useful” signals is increased.For instance, in the previously described example, the DPCH is boostedby increasing the target SIR (Signal to Interference Ratio) of the RadioResource Connection (RRC). A higher target SIR directly translates to ahigher desired signal (DPCH) over other unwanted signals (e.g.,including noise).

A number of other methods for improving reception of the useful signalsmay be substituted as well. For example, in other embodiments, thechannel coding of the one or more desired or “useful” signals may beadjusted dynamically. As readily appreciated, various modulationconstellations are more or less susceptible to quantization errors. Forexample, Binary Phase Shift Keying (BPSK) is less susceptible toquantization errors than Quadrature Phase Shift Keying (QPSK).Similarly, various higher-order constellations e.g., 16-QAM, 64-QAM,256-QAM, etc. (Quadrature Amplitude Modulation) are progressively morequantization error prone than lower-order constellations. Accordingly,some higher-order constellations are only used for low noiseenvironments. Hence, the higher order constellations may additionallyconsider the “sweet spot” range, in which (i) each symbol can bereliably distinguished over noise, and (ii) each symbol can be fullyrepresented in the available fixed point hardware. For example, atradeoff can be made between using high-order constellations with largertarget SIRs, or conversely lowering the constellation order andretaining (or even lowering) the target SIR.

In other embodiments, additional hardware elements are activated ordeactivated. In one such embodiment, the receiver enables supplementalfixed point extension hardware during high likelihood periods forquantization errors. For example, during normal operation, fixed pointarithmetic is set to eight (8) bits. During appropriate situations,additional extension hardware is enabled, supporting fixed pointarithmetic of ten (10), twelve (12) bits, etc. In yet other embodiments,the transmitter and receiver may enable specialized modulation ortransmission rate hardware.

Moreover, it should also be noted that constellation symbols are highlysusceptible to quantization errors, whereas transmission rate is not.Since the raw data rate is a combination of constellation complexity andtransmission rate, it is appreciated that a tradeoff between these twofactors may influence serving device operation. For example, the servingdevice may determine that the desired signal should be transmitted usingthe same constellation at the same rate, but increasing the transmitpower. Alternatively, the serving device may switch to a faster transmitrate using a lower complexity constellation; so as to remain at the sametransmit power. Other variations are described in greater detailsubsequent hereto (see “Exemplary Base Station Apparatus, ExemplaryMobile Apparatus” discussions presented below).

Referring now to FIG. 7, one exemplary implementation of the generalizedmethod of FIG. 6 for improving signal reception based on one or moreestimations of network load 700 is illustrated. At step 702, the CPICHand N₀ are measured. The CPICH E_(c)/N₀ is highly correlated to thenetwork load of the NodeB. If the CPICH/N₀ exceeds −7 dB, then themobile device assumes that the NodeB is operating with very littlenetwork load. In contrast, if the CPICH/N₀ is below −7 dB, then themobile device assumes that the NodeB is operating with normal loads.

The exemplary receiver notifies the NodeB that the network load appearsto be too low; i.e., that quantization error may be a factor in Qualityof Service (QoS) (704). The NodeB responsively selects from one or morecorrective options. For example, as shown, at step 706, the NodeB setsthe target SIR to a higher minimum requirement (1 dB).

Since the NodeB must match a higher level of SIR for the UE, the NodeBincreases the DPCH power, respective to the CPICH (708).

In alternate embodiments, the NodeB may configure other parameters toreduce quantization noise experienced by the receiver. For example,other embodiments may select between increasing target SIR, changingtransmission rates, changing constellation orders, etc.

Exemplary Base Station Apparatus—

Referring now to FIG. 8, exemplary base station apparatus 800implementing the functionality previously described above is illustratedand described. The base station apparatus 800 of the illustratedembodiment generally takes the form factor of a stand-alone device foruse in a cellular network, although other form-factors (e.g.,femtocells, picocells, access points, mobile hotspots, components withinother host devices, etc.) are envisaged as well.

The apparatus of FIG. 8 includes one or more substrate(s) 802 thatfurther include a plurality of integrated circuits including aprocessing subsystem 804 such as a digital signal processor (DSP),microprocessor, PLD or gate array, or plurality of processingcomponents, RF transceiver(s), as well as a power management subsystem806 that provides power to the base station 800.

The processing subsystem 804 includes in one embodiment an internalcache memory, or a plurality of processors (or a multi-core processor).The processing subsystem 804 is preferably connected to a memorysubsystem 808 which may comprise SRAM, Flash, SDRAM, etc. The memorysubsystem may implement one or a more of DMA type hardware, so as tofacilitate rapid data access.

The exemplary apparatus 800, in some embodiments, implements some formof broadband access 810 to a Core Network entity, and/or access 812 toother apparatus 600. For instance, the broadband access may be providedby a DSL connection (i.e., via DSL subsystem), although otherinterfaces, whether wired or wireless, may be used in place of or incombination with the DSL subsystem. It is recognized by one of ordinaryskill that other broadband access schemes such as DOCSIS cable modem, T1line, WiMAX (i.e., IEEE Std. 802.16), ISDN, FiOS, microwave link,satellite link, etc. could be readily substituted, or used in tandemwith the aforementioned DSL interface.

The base station apparatus 800 also includes one or more RF modemsubsystems. The modem subsystems 814 enable the base station to provideservice to one or more subscriber devices. It is readily appreciatedthat in some implementations of the invention, multiple subsystems maybe required. For example, a base station may provide multiple RF modemsubsystems to provide, inter alia, multi-mode operation (e.g. GSM, GPRS,UMTS, and LTE) over multiple distinct air interfaces. The modemsubsystems 814 include a modem, RF frontend, and one or more antennas.

It is further noted that in some embodiments, it may be desirable toobviate some of the components presently illustrated (such as RFfrontend), or alternatively, the discrete components illustrated may bemerged with one another to form a single component.

As previously described, base station implementations of the inventiongenerate signaling for a communication link to one or more recipientdevices; the communication link is composed of a number of signals.Furthermore, at least one or more desired or “useful” signals areaddressed to the one or more recipient devices. The invention enabledbase station additionally generates signaling which is undesired or“ignored” for at least one or more of the recipient devices.

In one exemplary UMTS embodiment, a NodeB base station apparatus 800generates a Common Pilot Channel (CPICH) 552 to provide all userequipment (UE) with a common synchronization signal. The NodeB basestation apparatus also generates Dedicated Physical Channels (DPCH) 556to provide channels for control (Dedicated Physical Control Channel(DPCCH)), and data (Dedicated Physical Data Channel (DPDCH)) messagingdevoted to single UEs. Each DPCH is only received by one recipient UE.

The exemplary UMTS NodeB base station apparatus 800 is further adaptedto receive one or more indicia associated with an estimated orcalculated network load. As previously described, the UMTS NodeB isadapted to generate or receive measurements of CPICH/N₀, whichrepresents a measurement of the CPICH power to the total received signalpower. It is appreciated that the foregoing indicia may be readilysubstituted with analogous indicia of the type previously describedherein by one of ordinary skill, given the contents of the presentdisclosure.

In one aspect of the present invention, the NodeB 800 can dynamicallyadjust DPCH 556 modulation characteristics to reduce the impact and/orlikelihood of quantization error. In one exemplary embodiment, theadjustment entails increasing DPCH transmit power when an indiciaassociated with an estimate/determination of network load exceeds one ormore threshold values. In alternate embodiments, the DPCH transmit powermay be calculated via an algorithm, so as to enable adjustment inlinear, exponential, logarithmic, etc. progressions.

Furthermore, as previously mentioned, yet other alternative embodimentsmay improve quantization error rejection. Quantization error affectsvarious aspects of channel coding differently. Transmission power,antenna configuration, constellation type, transmission rate, channelcoding complexity, supplemental hardware operation, etc. are eachsubject to different degrees of quantization error susceptibility. Thus,in one implementation, the base station apparatus “intelligently”considers channel coding methods which reject both noise, andquantization error, such as via a computer program or other computerizedlogic implementing such functions.

Various channel coding methods are more or less susceptible toquantization errors. For example, constellation type can be greatlyaffected by quantization errors; in comparison, transmission rate islargely independent of quantization error. Thus, in another aspect ofthe invention, an operational rules engine related to the quantizationerror reduction techniques described herein is provided. This enginecomprises, in an exemplary embodiment, a series of software routines orother associated hardware/firmware environment adapted to control theoperation of the channel coding based on one or more operationalconsiderations.

For example, rules implemented by the rules engine may be codified as aseries of preferences or a logical hierarchy (e.g., changes totransmission power are preferred over changes to transmission rate;changes to constellation are preferred over changes to transmissionpower, etc.). Additionally, the rules engine may consider additionaloperational aspects beyond mere channel coding quality; for example,other aspects may include elements such as Quality of Service (QoS),subscriber permissions, business considerations, etc.

Other variants of the base station operation including channel codingimplementations, and rules engines parameters, may be readilyimplemented by an artisan of ordinary skill, given the presentdisclosure.

Exemplary Mobile Apparatus—

Referring now to FIG. 9, exemplary client (e.g., UE) apparatus 900implementing the methods of the present invention is illustrated.

The UE apparatus 900 includes a processor subsystem 904 such as adigital signal processor, microprocessor, field-programmable gate array,or plurality of processing components mounted on one or more substrates902. The processing subsystem may also comprise an internal cachememory. The processing subsystem 904 is connected to a memory subsystem908 comprising memory which may for example, comprise SRAM, Flash andSDRAM components. The memory subsystem may implement one or a more ofDMA type hardware, so as to facilitate data accesses as is well known inthe art.

The radio/modem subsystem 910 comprises a digital baseband, analogbaseband, TX frontend and RX frontend. The apparatus 900 furtherincludes an antenna assembly to receive service from one or more basestation devices 800. While specific architecture is discussed, in someembodiments, some components may be obviated or may otherwise be mergedwith one another (such as RF RX, RF TX and ABB combined, as of the typeused for 3G digital RFs) as would be appreciated by one of ordinaryskill in the art given the present disclosure.

The illustrated power management subsystem (PMS) 906 provides power tothe UE, and may comprise an integrated circuit and or a plurality ofdiscrete electrical components. In one exemplary portable UE apparatus,the power management subsystem 906 advantageously interfaces with abattery.

The user interface system 912 includes any number of well-known I/Oincluding, without limitation: a keypad, touch screen, LCD display,backlight, speaker, and microphone. However, it is recognized that incertain applications, one or more of these components may be obviated.For example, PCMCIA card type UE embodiments may lack a user interface(as they could piggyback onto the user interface of the device to whichthey are physically and/or electrically coupled).

The apparatus 900 may further include optional additional peripheralsincluding, without limitation, one or more GPS transceivers, or networkinterfaces such as IrDA ports, Bluetooth, WLAN, and/or WiMAXtransceivers, USB, FireWire, etc. It is however recognized that thesecomponents are not required for operation of the UE in accordance withthe principles of the present invention.

In the illustrated embodiment, the modem subsystem 910 additionallyincludes subsystems or modules for receiving signaling for acommunication link generated by one or more serving devices 800; whereinthe communication link comprises a number of signals. Additionally, themodem subsystem is adapted to separate (physically via filters, orlogically via arithmetic operations) at least one or more desired or“useful” signals from undesired signals.

In one exemplary UMTS implementation, the mobile device apparatus 900(UE) is adapted to receive one or more DPCHs (Dedicated PhysicalChannels) 556 intermixed with a Common Pilot Channel (CPICH) 552. Theexemplary UMTS UE apparatus 900 is further adapted to calculate andcommunicate one or more indicia associated with an estimated networkload. As previously described, the UE is adapted to measure CPICH/N₀which represents a measurement of the CPICH power to the total receivedsignal power. As with the base station apparatus, the foregoing indiciamay be readily substituted with analogous indicia by one of ordinaryskill, given the contents of the present disclosure.

The CPICH/N₀ measures the power allocated to the CPICH (E_(c)) relativeto the total received power spectral density (N₀). CPICH/N₀ is commonlymeasured by UMTS receivers for handover/hand-off operation (the CPICH/N₀of each base station within an “active set” is tracked, for efficientcell selection). In the exemplary UE 900, CPICH/N₀ is measured within aCDMA rake receiver adapted to search and correlate code “fingers”. Inone embodiment, one or more conditional events (e.g., the detection ofunusually high CPICH/N₀) trigger the delivery of a message to therelevant serving apparatus 800. Once the exemplary UE 900 transmits theone or more indicia to the serving apparatus 800 (base station), theserving apparatus modifies the DPCH channel qualities (e.g., powerallocated to a DPCH, etc.) to improve quantization error rejection.

Alternative embodiments of the UE 900 may directly activate ordeactivate internal hardware, thereby improving quantization errorrejection. For example, in one such embodiment, the receiver may havesupplemental fixed point extension hardware which is only active duringhigh likelihood periods for quantization errors. During normaloperation, fixed point arithmetic is set to eight (8) bits, andadditional extension logic is held in reset. When triggered inappropriate situations, the additional extension hardware can be pulledout of reset to supporting fixed point arithmetic of ten (10), twelve(12) bits, etc. Other variants of this scheme may simply power downextension hardware, further improving power consumption when not in use.

For example, one extendable hardware embodiment utilizes longer fixedpoint A/D conversion components. During normal operation, the extraleast significant bits (LSBs) or most significant bits (MSBs) areignored. After enabling extension hardware, the extra bits are passed tothe extension logic, providing the additional granularity to reducequantization error.

Other mobile device variants are readily implemented by an artisan ofordinary skill, given the present disclosure.

OFDMA Networks—

Consider OFDMA (Orthogonal Frequency Domain Multiple Access) scheme 1000of FIG. 10 which partitions the entire frequency band into subcarriers1002 which are further divided into time slots 1004; each subcarriertimeslot combination is a time-frequency resource 1006. Each receiver isallocated a number of the time-frequency resources. Commonimplementations of OFDMA receivers and transmitters use a Fast FourierTransform (FFT) and Inverse Fast Fourier Transform (IFFT), Each receivermust perform a FFT on the entire radio resource band (including unwantedtime-frequency resources), to extract their desired time-frequencyresources. The transmitter must transmit with enough power to ensurethat the receiver has sufficient fidelity to extract the desiredtime-frequency resources.

In scenarios where various time-frequency resources have varying powerlevels, the FFT or IFFT operation will be dominated by the more powerfultime-frequency resource. Thus, in some scenarios, low poweredtime-frequency resource components may not have enough fidelity to besuccessfully extracted.

For example, during normal operation a base station which istransmitting downlink OFDM signals to a number of receivers must adjustthe transmission power of each subcarrier dynamically, to compensate foreffects such as fast fading specific to each receiver, etc.Unfortunately, as previously noted, each receiver demodulates the entirefrequency resource with an FFT. Consequently, nearby devices receivewaveforms which are dominated by transmit power of unwantedtime-frequency resources. More specifically, as the time sampled data isconverted to the frequency domain to separate the carrier into theconstituent subcarriers, the subcarrier allocated to the nearbyreceiving device is relatively insignificant compared to the subcarrierswhich have been boosted due to fast fading effects.

Thus in accordance with various aspects of the present invention, theOFDMA base station can use a minimum safety margin for nearby receivers.The minimum safety margin ensures that every recipient can demodulatethe time-frequency resources, without quantization error.

Similarly, during normal operation a base station which is receivinguplink OFDM signals from a number of receivers may require the nearbymobile devices to ratchet down their transmission power and the fartheraway mobile devices to ratchet up their transmission power. However, thebase station must receive still receive sufficient signal quality fromthe nearby device to avoid quantization errors. Thus, in this example,the BS may require the nearby device to boost the uplink signal strengthby a safety margin to remove quantization error.

Business/Operational Rules Engine—

The degree of tolerance allowed by the base station for quantizationrejection may be directly related to various desirable qualities for thesubscriber; however, the inventive solution does sometimes operate atthe cost of other network operations. For example, increasing DPCHtransmission power improves reception by a first subscriber, yet alsoadversely affects neighboring subscribers. Thus, in another aspect ofthe invention, a business rules engine related to the quantization erroravoidance apparatus and techniques described herein is provided. Thisengine comprises, in an exemplary embodiment, a series of softwareroutines or other associated hardware/firmware environment adapted tocontrol the operation of the quantization error reduction operationspreviously described.

In effect, the business rules engine comprises a supervisory entity thatmonitors and selectively controls the congestion management andavoidance functions at a business (e.g., revenue, profit, and/or QoSlevel), so as to implement desired business rules. The rules engine canbe considered an overlay of sorts to the basic quantization errormanagement/avoidance algorithms. For example, the foregoing invention iswell suited to providing high data rates in relatively pristinereception conditions. Thus, in one such model, a serviceprovider/network operator may provide quantization-free boosted dataservices to customers willing to pay a premium, as an incentive for itshigher-tier customers, or even subsidized by other 3^(rd) parties.

Certain business models may offer such desirable qualities embodied inpremium equipment. For example, home use femtocells may support suchpreferential services. In yet other models, a cellular network operatormay provide various levels of quantization resistance. For instance, allUEs with a high data rate may be grouped within a first class, and lowerdata rate UEs may be grouped within a second class. Service may beprovided to both first and second class UEs, where the UEs of the secondclass have different resistance (e.g., higher CPICH/N₀ thresholds, etc.)

In yet another aspect of the present invention, it is appreciated thatthe foregoing solution may be used to enable otherwise less capabledevices. For example, a device having only six (6) bits of fixed bitresolution could be utilized within a relatively clear channel. WithinUMTS networks, such devices would always require higher DPCH power. Theimplications of limited operation for low cost, low capability devicesmay have many desirable business applications. Thus, given the presentdisclosure artisans may determine that lower cost implementations,having smaller fixed point arithmetic implementations may beimplemented. Such designs must still reliably distinguish each symbolover noise; however the designs greater susceptibility to quantizationerror can be overcome by increasing transmit power.

It will be recognized that while certain aspects of the invention aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of theinvention, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the invention disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the invention. Theforegoing description is of the best mode presently contemplated ofcarrying out the invention. This description is in no way meant to belimiting, but rather should be taken as illustrative of the generalprinciples of the invention. The scope of the invention should bedetermined with reference to the claims.

What is claimed is:
 1. A method for improving quantization rejection ofat least one signal among a plurality of signals and noise, theplurality of signals including at least one other known signal,comprising: transmitting the plurality of signals; receiving informationrelated to an estimated network load based on a measured firstattribute; and adjusting transmission characteristics of at least onebut not all of the plurality of signals based on the information;wherein the first attribute comprises a ratio of a first parameter of anetwork to a second parameter of the network.
 2. The method of claim 1,wherein the first parameter of the network comprises a common channelpower of a common channel, and the second parameter of the networkcomprises a total received signal power.
 3. The method of claim 2,wherein the network is compliant with a Universal MobileTelecommunications System (UMTS) standard(s), and the common channelcomprises a common pilot channel (CPICH).
 4. The method of claim 1,additionally comprising: comparing the received information to at leastone criterion; and based at least in part on a result of the comparing,selectively adjusting the transmission characteristics.
 5. The method ofclaim 1, wherein the act of adjusting the transmission characteristicsincludes signal amplification.
 6. The method of claim 1, wherein the actof adjusting the transmission characteristics includes lowering aconstellation order.
 7. The method of claim 1, wherein the act ofadjusting the transmission characteristics includes changing atransmission rate.
 8. The method of claim 1, wherein the act ofadjusting the transmission characteristics includes changing one or morefeedback parameters.
 9. A method for enhancing quantization performanceof at least one radio signal among a plurality of radio signals,comprising: transmitting the plurality of radio signals, thetransmission having a first radio attribute; receiving informationrelated to a network load based on the first attribute; and adjustingthe transmission characteristics of the at least one radio signal amongthe plurality of signals based on the information; wherein the firstradio attribute comprises a ratio of a common channel power to a totalreceived signal.
 10. The method of claim 9, wherein the act of adjustingcomprises: comparing the ratio to at least one threshold criterion; andbased at least in part on the result of the comparing, selectivelyperforming the adjusting of the transmission characteristics.
 11. Themethod of claim 9, wherein the at least one radio signal is a dedicatedchannel.
 12. The method of claim 9, wherein the plurality of radiosignals includes at least one common signal, at least one unwantedsignal, and at least one wanted signal.
 13. The method of claim 12,wherein the act of adjusting the transmission characteristics includessignal amplification of the at least one wanted signal.
 14. The methodof claim 12, wherein the act of adjusting the transmissioncharacteristics includes lowering a constellation order of the at leastone wanted signal.
 15. The method of claim 12, wherein the act ofadjusting the transmission characteristics includes changing atransmission rate of the at least one wanted signal.
 16. The method ofclaim 12, wherein the act of adjusting the transmission characteristicsincludes changing one or more feedback parameters of the at least onewanted signal.
 17. A wireless apparatus, the apparatus comprising: awireless interface, the wireless interface configured to receive aplurality of signals; logic configured to determine a network load; aprocessing device coupled to a memory; and a computer program comprisinga plurality of executable instructions resident within the memory that,when executed by the processing device causes the wireless apparatus to:receive a first signaling channel via the wireless interface; request asecond signaling channel; estimate a network load based on a ratio of afirst parameter of the network to a second parameter of the network; andtransmit information relating to the estimated network load; wherein thetransmitted information is configured to adjust one or more receptioncharacteristics of the second signaling channel.
 18. The apparatus ofclaim 17, wherein the wireless interface has multiple fixed pointcapabilities, and wherein the fixed point capability is a receptioncharacteristic determined by the information.
 19. The apparatus of claim17, wherein the reception characteristic is a target signal tointerference (SIR) level.
 20. The apparatus of claim 17, wherein thereception characteristic is negotiated with a serving device.
 21. Theapparatus of claim 17, wherein the information relating to the estimatednetwork load comprises an indication of a signal strength of the firstsignaling channel, relative to signal strengths of a plurality ofsignals.
 22. A serving apparatus, the apparatus comprising: a wirelessinterface, the wireless interface configured to transmit and receive aplurality of signals; a processing device coupled to a memory; and acomputer program comprising a plurality of executable instructionsresident within the memory that, when executed by the processing devicecause the serving apparatus to: receive a network load estimation viathe wireless interface from a mobile device; and responsively adjust oneor more transmission characteristics of at least one, but not all, ofthe plurality of signals to the mobile device; wherein the network loadestimation is based on a ratio of a first parameter of a network to asecond parameter of the network.
 23. A method for compensating for oneor more orthogonal signals having much higher transmission power than auser signal, and resulting quantization error in the user signal, themethod comprising: obtaining a network load estimation, the network loadestimation based on a ratio of a first parameter of a network to asecond parameter of the network; and responsively adjusting one or moretransmission characteristics of the user signal based at least in parton the network load estimation, the adjusting mitigating thequantization error.
 24. The method of claim 23, wherein the one or moreorthogonal signals comprises a pilot channel, and the adjusting the oneor more transmission characteristics of the user signal comprisesincreasing a transmission power of the user signal.